Pathogenic Fungus Colletotrichum Gloeosporioides Research Articles

Antagonistic Test of Bacteria Producing Siderophore and Protease Enzymes from The Rhizosfer of Peanut Plants on The Growth of Pathogenic Fungus Colletotrichum gloeosporioides

This study aims to determine the inhibitory effect of bacterial isolates producing siderophores and protease enzymes on the growth of the pathogenic fungus Colletotrichum gloeosporioides. The initial stage of research begins with the isolation of pathogenic bacteria and fungi, and is followed by testing the production of siderophores and protease enzymes. Bacteria were isolated from the rhizosphere of peanut plants, while pathogenic fungi were isolated from large chili fruit infected with anthracnose disease taken from Jelantik Village, Central Lombok Regency. Characterization of isolates for siderophore production used the Arnow method, while the protease enzyme production test used SKIM Milk Agar media. Next, the inhibition test of bacterial isolates against pathogenic fungi was carried out using the dual culture method. Characterization of potential isolates was carried out by observing bacterial colony morphology, gram staining and biochemical tests. The results of the siderophore production test showed that there was one isolate capable of producing siderophores with the isolate code RKT2. Meanwhile, the protease enzyme production test showed that all bacterial isolates produced protease enzymes, where isolate RKT9 had the highest Proteolytic Index, namely 1.57. The two isolates showed different inhibitory test results, namely isolate RKT2 had high inhibition, while RKT9 had low inhibition. The results of the research showed that a bacterial isolate (RKT2) from the rhizosphere of peanut plants was able to inhibit the growth of the pathogenic fungus Colletotrichum gloeosporioides in the high category.

High-Throughput Bioassay for Detection of Latent Fungi in Postharvest Produce.

Enormous fresh agricultural produce is wasted annually due to rots caused by pathogenic microorganisms. Most pathogenic fungi attack the harvested produce by penetrating the fruit at the field and remaining quiescent or latent until the fruit ripens or senescence. In this work, a recently developed simple, cost-effective, and high-throughput 96-well plate-based assay was applied to determine the presence of pathogenic fungi in their latent stage. The surface strands immobilized on the 96-well plate, only with the presence of the complementary RNA marker (enoyl-CoA hydratase (ECH)) of the latent fungal-pathogen Colletotrichum gloeosporioides will create a complex with the target and reporter (labeled with the horseradish peroxidase (HRP) enzyme) strands for positive signal generation. The developed assay demonstrated 3.1-fold higher specificity for the latent marker (ECH) of C. gloeosporioides compared to latent markers of other pathogenic fungi. A 2 nM detection limit of target strands was demonstrated, showing a high plate sensitivity, and was further validated with biological samples extracted from latent infection in tomato fruit. The developed assay provides a new economical tool for detecting the presence of latent RNA markers of pathogenic fungi in agricultural produce, ultimately improving postharvest decision-making and reducing postharvest losses.

A Review on Bio-Based Control of Post-Harvest Diseases

Bacillus subtilis non-pathogenic beneficial bacteria, promotes plant growth, disease resistance and tolerance to abiotic stresses. It produces bioactive substances with antibiotic properties and induces physiological features in plant metabolism without adverse effects on the environment or human health. Bacillus subtilis has been used to treat various postharvest diseases during handling, transportation and storage of various fresh fruits and vegetables. It is the first microorganism patented as a postharvest bio control agent for Brown rot of stone fruits, improving the post-harvest physiology of various fruit/vegetables. Bacillus strains AG1 and H110 have been shown to be effective against Vine wood fungal pathogens and post-harvest pathogens. They have been shown to reduce symptoms of Anthracnose in fruit caused by fungal pathogens Colletotrichum gloeosporioides and C. acutatum and White rot caused by Botryosphaeria dothidea. Endophytic Bacillus strains have been developed that can colonize plant tissues and live in the same ecological niches as pathogens, thus preventing post-harvest diseases and improving preservation during storage. Bacillus strains induce auxins, cytokinins, gibberellins, ABA, JA and SA in plants, which can stimulate plant growth under stressful conditions. Endophytic bacteria can induce ISR against pathogens and abiotic stressors, extending the shelf life of stored fruits and vegetables. Microbial antagonists can be applied after harvest to control fruit and vegetable diseases, but a single microbial strain cannot prevent all fruits/vegetables from decaying during storage. Combining diverse antagonistic microorganisms with diverse microbial activity and combining various bio-controlling characteristics can prevent post-harvest decay on fruits/vegetables.

Antagonistic Potential of Endophytic Bacteria from Shallot against Colletotrichum gloeosporioides Causing Anthracnose Disease

Anthracnose, a highly destructive disease in fruit crops, is primarily caused by the widespread fungal pathogen Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. Currently, chemical fungicides are commonly used to effectively prevent anthracnose infection and spread. However, the excessive and prolonged use of these chemicals has led to the development of resistance in pathogenic fungi. Moreover, chemical fungicides contribute to environmental pollution due to their slow degradation and non-specific toxicity to non-target organisms. As a result, researchers have increasingly focused on developing and implementing alternative methods that are less reliant on fungicides and more environmentally friendly. Endophytic bacteria have been acknowledged as potential biocontrol agents for effectively managing plant diseases. They provide safer alternatives for controlling fungal infections, offering a more environmentally friendly approach compared to chemical fungicides. The objective of this study was to examine the inhibitory effects of fourteen isolates derived from shallot plants on C. gloeosporioides through an in vitro dual culture assay. The isolates were purified and identified as various species belonging to the Bacillus genus. The inhibitory activity was assessed by measuring the percentage inhibition of radial growth. The results indicated that B. velezensis exhibited the highest antagonistic activity (P<0.05), reducing radial growth by 90% compared to the non-treated control. This was followed by B. subtilis at 80%, B. cereus at 39%, B. megaterium at 38%, and B. licheniformis with the lowest inhibition rate at 36%. Furthermore, the production of antifungal volatiles significantly contributed to the antagonistic activity (P<0.05), particularly with B. licheniformis volatiles inhibiting the mycelial growth of C. gloeosporioides. The results of this study indicate that Bacillus species exhibit significant antifungal characteristics and have the potential to be used as biocontrol agents for effectively managing Anthracnose in a variety of crops.

Natural Flora Is Indiscriminately Hosting High Loads of Generalist Fungal Pathogen Colletotrichum gloeosporioides Complex over Forest Niches, Vegetation Strata and Elevation Gradient.

Crop pathogenic fungi may originate from reservoir pools including wild vegetation surrounding fields, and it is thus important to characterize any potential source of pathogens. We therefore investigated natural vegetation's potential for hosting a widespread pathogenic group, Colletotrichum gloeosporioides species complex. We stratified sampling in different forest environments and natural vegetation strata to determine whether the fungi were found preferentially in specific niches and areas. We found that the fungi complex was fairly broadly distributed in the wild flora, with high prevalence in every study environment and stratum. Some significant variation in prevalence nevertheless occurred and was possibly associated with fungal growth conditions (more humid areas had greater prevalence levels while drier places had slightly lower presence). Results also highlighted potential differences in disease effects of strains between strata components of study flora, suggesting that while natural vegetation is a highly probable source of inoculums for local crops nearby, differences in aggressiveness between vegetation strata might also lead to differential impact on cultivated crops.

Efficient control of the fungal pathogens Colletotrichum gloeosporioides and Penicillium digitatum infecting citrus fruits by native soilborne Bacillus velezensis strains

Destruction of citrus fruits by fungal pathogens during preharvest and postharvest stages can result in severe losses for the citrus industry. Antagonistic microorganisms used as biological agents to control citrus pathogens are considered alternatives to synthetic fungicides. In this study, we aimed to identify fungal pathogens causing dominant diseases on citrus fruits in a specialized citrus cultivation region of Vietnam and inspect soilborne Bacillus isolates with antifungal activity against these pathogens. Two fungal pathogens were characterized as Colletotrichum gloeosporioides and Penicillium digitatum based on morphological characteristics and ribosomal DNA internal transcribed spacer sequence analyses. Reinfection assays of orange fruits confirmed that C. gloeosporioides causes stem-end rot, and P. digitatum triggers green mold disease. By the heterologous expression of the green fluorescent protein (GFP) in C. gloeosporioides using Agrobacterium tumefaciens-mediated transformation, we could observe the fungal infection process of the citrus fruit stem-end rot caused by C. gloeosporioides for the first time. Furthermore, we isolated and selected two soilborne Bacillus strains with strong antagonistic activity for preventing the decay of citrus fruits by these pathogens. Molecular analyses of 16 S rRNA and gyrB genes showed that both isolates belong to B. velezensis. Antifungal activity assays indicated that bacterial culture suspensions could strongly inhibit C. gloeosporioides and P. digitatum, and shield orange fruits from the invasion of the pathogens. Our work provides a highly effective Bacillus-based preservative solution for combating the fungal pathogens C. gloeosporioides and P. digitatum to protect citrus fruits at the postharvest stages.

Hypovirulence of Colletotrichum gloesporioides Associated with dsRNA Mycovirus Isolated from a Mango Orchard in Thailand.

The pathogenic fungus Colletotrichum gloeosporioides causes anthracnose disease, which is an important fungal disease affecting the production of numerous crops around the world. The presence of mycoviruses, however, may have an impact on the pathogenicity of the fungal host. Here, we describe a double-stranded RNA (dsRNA) mycovirus, which was isolated from a field strain of C. gloeosporioides, Ssa-44.1. The 2939 bp genome sequence comprises two open reading frames (ORFs) that encode for a putative protein and RNA-dependent RNA polymerase (RdRp). The Ssa-44.1 mycovirus is a member of the unclassified mycovirus family named Colletotrichum gloeosporioides RNA virus 1 strain Ssa-44.1 (CgRV1-Ssa-44.1), which has a phylogenetic similarity to Colletotrichum gleosporioides RNA virus 1 (CgRV1), which was isolated from citrus leaves in China. In C. gloeosporioides, CgRV1-Ssa-44.1 was shown to be linked to hypovirulence. CgRV1-Ssa-44.1 has a low spore transfer efficiency but can successfully spread horizontally to isogenic virus-free isolates. Furthermore, CgRV1-Ssa-44.1 had a strong biological control impact on C. gloeosporioides on mango plants. This study is the first to describe a hypovirulence-associated mycovirus infecting C. gloeosporioides, which has the potential to assist with anthracnose disease biological management.

Role of Reactive Oxygen Species against Pathogens in Relation to Postharvest Disease of Papaya Fruit

Reactive oxygen species (ROS) play an active role in plant defense. Polyphenol oxidase (PPO) and peroxidase (POD) participate in the synthesis of phytoalexins. The comparative activities of ROS, including hydrogen peroxide (H2O2), superoxide anions (O2−), and hydroxyl radicals (·OH), against the fungal pathogen Colletotrichum gloeosporioides from papaya fruit were evaluated. The effects of ROS on PPO and POD activities in papaya fruit inoculated with C. gloeosporioides and the development of natural decay in intact fruit were also investigated. ·OH was the most effective in inhibiting conidial germination and mycelial growth of C. gloeosporioides in vitro. However, 20 or 30 mM H2O2 exhibited the best control of the three ROS treatments at ameliorating the disease symptoms associated with the highest levels of PPO and POD activities in papaya fruit. Furthermore, the activities of PPO and POD negatively correlated with the disease index. Overall, H2O2 treatments can induce the resistance of papaya fruit against C. gloeosporioides owing to the enhanced activities of PPO and POD. Treatment with 20 mM H2O2 also significantly reduced the incidence of decay in intact papaya fruit in semi-commercial experiment, which could make it a potential alternative manner to control postharvest disease in papaya fruit.

Dynamics of Pathogenic Fungi in Field Hedges: Vegetation Cover Is Differentially Impacted by Weather.

Landscape effects might impede or increase spore dispersal and disease risk for crops, as trees and hedges buffer winds and can behave as spore traps, therefore limiting diffusion of fungi, or, on the contrary, behave as disease relay once vegetation is infected and become inoculum sources. In this study, we investigated weekly prevalence of the pathogenic fungus Colletotrichum gloeosporioides on guava tree leaves, differentiating impacts of leaf height on tree, age, and location within leaf. We first estimated differences in prevalence for each covariate, and then related infection rates to weather effects during the year. Our results highlighted a great variance of prevalence among individual trees, and a lower contamination of tree tops, as well as a tendency for greater odds of infection in tips of young leaves compared to older ones. Last, we show evidence that individual tree contaminations are associated with different disease dynamics: early and dispersal-based, late and growth-based, as well as with intermediate dynamic ranges. Pathogen infection dynamics will thus be greatly impacted by cover characteristics at local scale, and tree cover should not be perceived as homogeneously driving disease levels.

Detection of necrotrophic DNA marker of anthracnose causing Colletotrichum gloeosporioides fungi in harvested produce using surface plasmon resonance

Agriculture and food crops monitoring is extremely important for securing the food supply chain to human society. Here, we developed a highly specific detection method for monitoring pathogenic fungus Colletotrichum gloeosporioides using necrotrophic DNA biomarker as the recognition element and surface plasmon resonance (SPR) as transducing mechanism in the prism coupling configuration. The sensor shows its response for a wide range of concentrations from pM to μM of target DNA sequence using a complementary DNA probe immobilized on the sensor surface, which could detect concentrations as low as 7 pM. The detection limit is found to be comparable with conventional molecular-based detection platforms, achieved due to optimized spectral SPR bimetallic substrate with subpixel resolution obtained by post processing. The response time of the sensor for detection is less than 30 min at room temperature. The quick detection scheme of the sensor may facilitate the screening of a large number of samples acquired for the sorting of harvested produce. This sensor is fast, reliable, cost-effective, and can be miniaturized for portability for the screening of real samples (mRNA) in the field and packaging house.

Novel dirhenium(III,III) complexes with bridging diphenylphosphinomethane and dithiocarbamato ligands: A combined experimental and theoretical study

Sodium salts of dimethyldithiocarbamate (LMe), diethyldithiocarbamate (LEt) and pyrrolidinedithiocarbamate (LPyr) react with the double-bonded diamagnetic dirhenium(III,III) complex Re2(μ-dppm)2(μ-Cl)2Cl4 (1) (dppm = Ph2PCH2PPh2) in refluxing ethanol to afford the diamagnetic substitution products of the type [Re2(µ-dppm)(η2-LR)2(µ-η2-LR)2](PF6)2, where LR represents the dithiocarbamato ligands [LR = S2CNMe2, 2(LMe); S2CNEt2, 2(LEt) and S2CN(CH2)4, 2(LPyr)]. The complexes were isolated as hexafluoridophosphate salts. These are the first examples of dirhenium(III,III) complexes that contain bridging dithiocarbamato ligand along with the dppm ligand. The spectral and electrochemical properties of the complexes are reported. The identity of 2(LMe) and 2(LEt) was established by single crystal X-ray structure determination (Re─Re distance ~ 2.55 Å) and is shown to have edge-shared bioctahedral structure. The electronic structure and the absorption spectra of the complexes are scrutinized by the density functional theory (DFT) and time-dependent density functional theory (TD-DFT) analyses. DFT analysis shows that the highest occupied molecular orbitals are mainly metal δ* based orbitals. The complex 2(LEt) was tested for its ability to exhibit DNA-binding activity. The antifungal activity of the complex 2(LEt) was also determined against the fungal pathogen Colletotrichum gloeosporioides (CG).

Postharvest application of partitioned plant extracts from Sinaloa, Mexico for controlling papaya pathogenic fungus Colletotrichum gloeosporioides

Anthracnose compromises papaya production and is caused by the fungus Colletotrichum gloeosporioides. New natural alternatives to synthetic fungicides are necessary to control anthracnose due to health and environmental concerns. In this regard, extracts of plants from Sinaloa, Mexico, have shown activity against molds and yeasts with medical and agricultural importance; however, their protective effect on papaya fruit infected with C. gloeosporioides is still unknown. This study aimed to assess the in vitro and in vivo antifungal activities of crude methanol extracts (ME) from nine plants from Sinaloa, Mexico, and their semi-purified fractions. In vitro assays showed that C. gloeosporioides was inhibited by 7 out the 16 extracts assessed; Psidium sartorianum (pulp), Echeveria kimnachii (leaf), and Vitex mollis (VM) (pulp) had the highest antifungal activity and the lowest toxicity against Artemia salina. When these extracts were fractionated, the activity increased. Hexane (HF-VM) and ethyl acetate (EAF-VM) fractions of V. mollis were the most effective fractions (MEF), with the lowest minimum inhibitory concentration (MIC) (20 and 30 mg/mL, respectively). The in vivo results showed that HF-VM at 40 mg/mL (HF40) was the best to delay the apparition and development of anthracnose symptoms. Coumarins, alkaloids and terpenes were detected on this fraction by tube assays or thin layer chromatography (TLC). Moreover, this treatment decreased water loss and did not affect any of the quality parameters assessed. Therefore, HF40 is a natural alternative to thiabendazole (TBZ) in the protection of papaya fruit against anthracnose.

Quorum sensing-mediated inter-specific conidial anastomosis tube fusion between Colletotrichum gloeosporioides and C. siamense

Many plant pathogenic filamentous fungi undergo fusion of conidia through conidial anastomosis tubes (CATs), which is believed to facilitate horizontal gene transfer between species. We discovered a remarkable inter-specific CAT fusion between two important plant fungal pathogens Colletotrichum gloeosporioides and C. siamense. In an invitro assay, under no selection pressure, the inter-specific CAT fusion was preferred with higher frequency (25% ± 5%) than intra-specific CAT fusion (11% ± 3.6%). Different stages of CAT fusion viz. CAT induction, homing, and fusion were observed during this inter-specific CAT fusion. The CAT fusion was found to be higher in absence of nutrients and under physiological stresses. This CAT fusion involved a quorum sensing phenomenon, wherein the CAT induction was dependent on conidial density and the putative quorum sensing molecule was extractable in chloroform. Movement of nuclei, mitochondria, and lipid droplets were observed during the CAT fusion. Post CAT fusion, the resulting conidia gave rise to putative heterokaryotic progenies with variable colony characteristics as compared to their parental strains. Few heterokaryons showed variable AFLP banding pattern compared to their parental strains, thereby suggesting a possible genetic exchange between the two species through CAT fusion. The heterokaryotic progenies exhibited varied fitness under different stress conditions. Our study illustrated a possible role of inter-specific CAT fusion in generation of genetic and phenotypic diversity in these fungal pathogens.

Antifungal Activity of Cyclic Tetrapeptide from Bacillus velezensis CE 100 against Plant Pathogen Colletotrichum gloeosporioides.

The aim of this study was to investigate the antifungal activity of a cyclic tetrapeptide from Bacillus velezensis CE 100 against anthracnose-causing fungal pathogen Colletotrichum gloeosporioides. Antifungal compound produced by B. velezensis CE 100 was isolated and purified from ethyl acetate extract of B. velezensis CE 100 culture broth using octadecylsilane column chromatography. The purified compound was identified as cyclo-(prolyl-valyl-alanyl-isoleucyl) based on mass spectrometer and nuclear magnetic resonance analyses. This is the first report of the isolation of a cyclic tetrapeptide from B. velezensis CE 100 culture filtrate. Cyclic tetrapeptide displayed strong antifungal activity at concentration of 1000 µg/mL against C. gloeosporioides mycelial growth and spore germination. Our results demonstrate that the antifungal cyclic tetrapeptide from B. velezensis CE 100 has potential in bioprotection against anthracnose disease of plants caused by C. gloeosporioides.

Biotransformation of pungent constituents from ginger (Zingiber officinale Roscoe) by Colletotrichum gloeosporioides yields oxidative ortho–ortho coupling products

This work investigated the biotransformation of ginger constituents (zingerone, [6]-shogaol, [6]-gingerol, and methyl-[6]-gingerol) by the pathogenic fungus Colletotrichum gloeosporioides. Experiments were carried out with and without deuterium-labelled compounds. The product metabolites were analyzed by liquid chromatography coupled to tandem mass spectrometry and liquid chromatography solid phase extraction-nuclear magnetic resonance. Substrates supplied to the fungus were incorporated into metabolic pathways mostly by oxidation reactions, including aromatic carbon–carbon coupling. Zingerone and [6]-gingerol biotransformation products included biphenol dimers. A biodegradation pathway for biphenol formation was proposed based on the presence of the intermediate 4-(2-hydroxyethyl)-2-methoxyphenol, commonly identified from [6]-gingerol and [6]-shogaol biodegradation. This intermediate likely originates from a Baeyer–Villiger reaction followed by hydrolysis. The C–C coupling of molecules could result in phenolic oxidative ortho–ortho coupling, suggesting that biphenol dimers are products of C. gloeosporioides laccase catalysis.

The Incorporation of Amplified Metal-Enhanced Fluorescence in a CMOS-Based Biosensor Increased the Detection Sensitivity of a DNA Marker of the Pathogenic Fungus Colletotrichum gloeosporioides

Half of the global agricultural fresh produce is lost, mainly because of rots that are caused by various pathogenic fungi. In this study, a complementary metal-oxide-semiconductor (CMOS)-based biosensor was developed, which integrates specific DNA strands that allow the detection of enoyl-CoA-hydratase/isomerase, which is a quiescent marker of Colletotrichum gloeosporioides fungi. The developed biosensor mechanism is based on the metal-enhanced fluorescence (MEF) phenomenon, which is amplified by depositing silver onto a glass surface. A surface DNA strand is then immobilized on the surface, and in the presence of the target mRNA within the sample, the reporter DNA strand that is linked to horseradish peroxidase (HRP) enzyme will also bind to it. The light signal that is later produced from the HRP enzyme and its substrate is enhanced and detected by the coupled CMOS sensor. Several parameters that affect the silver-deposition procedure were examined, including silver solution temperature and volume, heating mode, and the tank material. Moreover, the effect of blocking treatment (skim milk or bovine serum albumin (BSA)) on the silver-layer stability and nonspecific DNA absorption was tested. Most importantly, the effect of the deposition reaction duration on the silver-layer formation and the MEF amplification was also investigated. In the study findings a preferred silver-deposition reaction duration was identified as 5–8 min, which increased the deposition of silver on the glass surface up to 13-times, and also resulted in the amplification of the MEF phenomenon with a maximum light signal of 50 relative light units (RLU). It was found that MEF can be amplified by a customized silver-deposition procedure that results in increased detection sensitivity. The implementation of the improved conditions increased the biosensor sensitivity to 3.3 nM (4500 RLU) with a higher detected light signal as compared to the initial protocol (400 RLU). Moreover, the light signal was amplified 18.75-, 11.11-, 5.5-, 11.25-, and 3.75-times in the improved protocol for all the tested concentrations of the target DNA strand of 1000, 100, 10, 3.3, and 2 nM, respectively. The developed biosensor system may allow the detection of the pathogenic fungus in postharvest produce and determine its pathogenicity state.

Biological control of poplar anthracnose caused by Colletotrichum gloeosporioides (Penz.) Penz. & Sacc.

Poplar anthracnose is one of the most serious diseases caused by the fungal pathogen Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. Biocontrol is an efficient green way for the disease control, and numerous researches have focused on exploring the potential biocontrol bacteria strains against C. gloeosporioides. In this study, antifungal activities against C. gloeosporioides of 108 rhizosphere soil isolates from healthy polar plants were investigated in vitro by the dual culture assay. The results suggested that strain ZSH-1 showed the highest level of antifungal activity, as it inhibited C. gloeosporioides at a distance of 10.00 mm. Based on the morphological, physiological-biochemical characteristics, and phylogeny analysis, strain ZSH-1 was identified as Bacillus subtilis. The sterile culture filtrate, crude protein, and crude lipopeptide extracts from the culture filtrate, and volatile compound(s) of ZSH-1 displayed a strong antagonism towards 7 fungal phytopathogens (C. gloeosporioides, Fusarium oxysporum, Alternaria tenuissima, Cytospora chrysosperma, Botryosphaeria dothidea, Mucor sp., and Absidia sp.), with inhibition rates ranging from 44.0 to 89.1%, 26.7 to 85.4%, 11.6 to 89.7%, and 7.8 to 63.2%, respectively. Moreover, ZSH-1 exhibited cell wall-degrading traits by producing 3 lytic enzymes (cellulose, β-1,3-glucanase, and protease). Finally, the greenhouse studies also revealed that strain ZSH-1 had a 47.6% (12 days) efficacy in controlling poplar anthracnose when compared with the control. In concluding, obtained results demonstrate the potential biocontrol effect of B. subtilis ZSH-1, and it can be used as a promising biocontrol agent against poplar anthracnose and other fungal phytopathogens.

Glycosylated flavonoids: fruit's concealed antifungal arsenal.

Fruit defense against pathogens relies on induced and preformed mechanisms. The present contribution evaluated performed resistance of red and green mango fruit against the fungal pathogen Colletotrichum gloeosporioides and identified the main active antifungal components. High-performance liquid chromatography analysis of nonhydrolyzed mango peel extracts identified major anthocyanin peaks of glycosylated cyanidin and methylcyanidin, and flavonol peaks of glycosylated quercetin and kaempferol, which were more abundant on the 'red side' of red mango fruit. Organic extracts of red vs green mango peel were more efficient in inhibiting C.gloeosporioides. Transcriptome analysis of the mango-C.gloeosporioides interaction showed increased expression of glucosidase genes related to both fungal pathogenicity and host defense. Glucosidase treatment of organic peel extract increased its antifungal activity. Additionally, quercetin and cyanidin had significantly higher antifungal activity than their glycosylated derivatives. Peel extract volatiles treated with glucosidase had antifungal activity. GCMS analysis identified 15 volatiles after glucosidase hydrolysis, seven of them present only in red fruit. These results suggest that the fruit obtains a concealed arsenal of glycosylated flavonoids in its peel when they are hydrolyzed by β-glucosidase that is induced in both fungus and host during infection process, become more toxic to the fungal pathogen, inhibiting decay development.

Dirhamnolipid Produced by the Pathogenic Fungus Colletotrichum gloeosporioides BWH-1 and Its Herbicidal Activity.

Fungal phytotoxins used as ecofriendly bioherbicides are becoming efficient alternatives to chemical herbicides for sustainable weed management. Previous study found that cultures of the pathogenic fungus Colletotrichum gloeosporioides BWH-1 showed phytotoxic activity. This study further isolated the major phytotoxin from cultures of the strain BWH-1 using bioactivity-guided isolation, by puncturing its host plant for an activity test and analyzing on the HPLC-DAD-3D mode for a purity check. Then, the active and pure phytotoxin was characterized as a dirhamnolipid (Rha-Rha-C10-C10) using the NMR, ESIMS, IR and UV methods. The herbicidal activity of dirhamnolipid was evaluated by the inhibition rate on the primary root length and the fresh plant weight of nine test plants, and the synergistic effect when combining with commercial herbicides. Dirhamnolipid exhibited broad herbicidal activity against eight weed species with IC50 values ranging from 28.91 to 217.71 mg L−1 and no toxicity on Oryza sativa, and the herbicidal activity could be synergistically improved combining dirhamnolipid with commercial herbicides. Thus, dirhamnolipid that originated from C. gloeosporioides BWH-1 displayed the potential to be used as a bioherbicide alone, or as an adjuvant added into commercial herbicides, leading to a decrease in herbicides concentration and increased control efficiency.

Molecular characterization of a novel mycovirus from the plant pathogenic fungus Colletotrichum gloeosporioides.

In this study, we report the molecular characterization of a novel mycovirus in a phytopathogenic fungus of the species Colletotrichum gloeosporioides, which we named "Colletotrichum gloeosporioides RNA virus 1" (CgRV1). The virus has a dsRNA genome of 2,975 bp and possesses two non-overlapping open reading frames (ORFs 1 and 2). The smaller ORF1 encodes a protein of unknown function, and the larger ORF2 encodes the RNA-dependent RNA polymerase (RdRp). Phylogenetic analysis based on the RdRp sequence showed that CgRV1 clustered with and is closely related to unclassified mycoviruses that are distinct from members of the family Partitiviridae.